This is a first multidimensional study of the clinical, psychosocial and biological risk factors for suicide in patients with Borderline Personality Disorder (BPD), a disorder with a completed suicide rate of 3-9%. Forty patients with BPD will be compared to 40 patients with Major Depression (MDE) and 40 normal controls on measures of central serotonergic responsiveness, including prolactin response to challenging with d, 1, fenfluramine during PET scanning with FDG.